1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting apparatus and a piezoelectric element, and to a method for manufacturing a piezoelectric element.
2. Related Art
A liquid ejecting head is incorporated in a liquid ejecting apparatus, such as an ink jet printer. In this instance, the liquid ejecting head is used for ejecting ink droplets to fly them, so that the ink jet printer can deposit the ink on a medium such as paper and thus perform printing (see JP-A-2009-283950).
In general, a liquid ejecting head includes a piezoelectric element that applies a pressure to liquid to eject the liquid through a nozzle. Such a piezoelectric element may have a structure in which a piezoelectric member made of a piezoelectric material capable of electromechanical conversion, such as a crystallized piezoelectric ceramic, is disposed between two electrodes. This type of piezoelectric element can be deformed by the voltage applied by the two electrodes.
It is preferable that piezoelectric materials used for this application have high electromechanical conversion efficiency or other piezoelectric characteristics. Lead zirconate titanate (PZT) is superior in piezoelectric characteristics to other piezoelectric materials, and PZT materials have been studied and developed. However, in view of environmental issues, non-lead piezoelectric materials become desirable, including lead-free materials and lead-less materials whose lead content has been minimized.
For example, (K,Na)NbO3 (KNN, potassium sodium niobate) is theoretically considered to be a lead-free piezoelectric material having high piezoelectric characteristics.
However, while KNN can form an alignment layer preferentially oriented in a predetermined direction on oxide electrodes such as those of strontium-ruthenium complex oxides (SrRuOx, abbreviated as SRO) or strontium-titanium complex oxides (SrTiOx, abbreviated as STO), it is difficult to form such an NKK alignment layer on a Pt (platinum) electrode, which is generally used for piezoelectric elements.